The invention relates to composite components often found in gas turbine engines and, particularly, composite to metallic connections often found in gas turbine engines. Bypass gas turbine engines of the turbofan type generally include a forward fan and booster compressor, a middle core engine, and an aft low pressure power turbine. A low pressure turbine rotatably drives the fan and booster compressor via a low pressure shaft, all of which form the low pressure rotor. Composite components have been developed, such as blades, vanes and static structures, and are often used in these gas turbine engines. In particular, composite airfoils have been developed and used in blades for rotatable stages of the booster compressor and in stator vanes disposed between and upstream and downstream of the blades as well in other sections of the engine such as in the fan section (fan outlet guide vanes).
It is known to manufacture aircraft gas turbine engine blade and vane airfoils from composite materials. It has been found difficult to attach composite components, such as these vanes and airfoils, to a metallic component. One particular embodiment lies in the attachment of composite airfoils to a metallic component for mounting the blade or vane to the component, such as a metallic rotor or stator portion of the engine. This is a challenge due to the magnitude of loads and limited size of the components. Typically, the attachments of these composite parts are the challenging part of that implementation. It is desired to have an integral composite/metallic attachment system that takes advantage of the composite weight. Simple adhesive bonds and joints including mechanical fasteners have been used in the past to join these two systems. The bonded joints are subject to forces and moments that tend to dislodge the composite/metallic joint, and more particularly, the composite component, such as an airfoil, from a metallic component, such as a mount of the blade or vane. On the other hand, mechanically fastened joints require fabricating openings that cut into the fibers of the composite structure that may weaken the overall capability of the composite structure. To address this issue, the composite structure may include additional strengthening at the joint, negatively affecting any weight benefit.
It is therefore highly desirable to provide a joining means for securely and robustly joining composite components and metallic components that is capable of resisting forces and moments that tend to dislodge the composite components from the metallic components and without weakening the composite structure. It is additionally desirable to provide a means for securely and robustly joining composite components, such as airfoils, in both gas turbine engine rotor and fan frame assemblies to metallic components, such as a metallic mount of the blade or vane, and thus enable the composite/metallic joint to resist forces and moments that tend to dislodge the composite airfoils from the metallic mount.